Ultrasonic transducers emit ultrasonic acoustic waves when an electrical signal is applied to thereto and/or produce an electronic signal when an ultrasonic signal is incident thereon.
One type of ultrasonic transducer is known as a piezoelectric ultrasonic transducer. A piezoelectric ultrasonic transducer comprises a piezoelectric material disposed between electrodes. The application of a time-varying electrical signal will cause a mechanical vibration across the transducer, resulting in emission of an acoustic signal. By contrast, the application of a time-varying acoustic signal to the piezoelectric ultrasonic transducer will cause a time-varying electrical signal to be generated by the piezoelectric material of the transducer. Many known ultrasonic transducers have a narrow transmission beam and a narrow acceptance angle.
Ultrasonic transducers may be used in a variety of applications. For example, ultrasonic transducers may be used in measurement and error detection applications. One type of measurement applications is based on the degree of absorption of ultrasonic waves between an ultrasonic transmitter and an ultrasonic receiver.
One known arrangement comprising ultrasonic transducers for absorption measurement utilizes common narrow beam transducers and is shown in FIG. 1. An ultrasonic apparatus 100 includes a transmitter support 101 and a receiver support 102. The transmitter support 101 includes a first receptacle 103, in which a transmit ultrasonic transducer 104 is provided. The receiver support 102 includes a second receptacle 105, in which a receive transducer 106 is provided. The transmit ultrasonic transducer 104 emits a comparatively narrow ultrasonic beam 107 (less than approximately 10°) that is received by the receive ultrasonic transducer 106, which also has a comparatively narrow acceptance angle (less than approximately 10°)
The transmit and receive transducers 104, 105 are arranged in at an angular offset relative to one another, and as shown in FIG. 1. The overall angular arrangement is required to avoid the creation of standing waves (i.e., through constructive or destructive interference) between the transducers 104, 105 and the absorptive media that is placed between the transducers 104, 105. In addition, the transmit and receive transducers 104, 105 are also tilted to avoid standing waves between transmit ultrasonic transducer 104 and the receive ultrasonic transducer 106. As can be appreciated by one of ordinary skill in the art, such standing waves can adversely impact the detected amplitude of the acoustic waves at the receive transducer 106. In applications that rely on comparatively accurate amplitude measurement and detection, such as absorption measurements, standing waves produce an unacceptable level of measurement uncertainty.
While the known ultrasonic apparatus setup 100 is useful in reducing the occurrence of standing waves between the transmit and receive transducers 104, 106, there are drawbacks to the apparatus 100. For example, the precise location the first and second receptacles 103, 105 adds to the complexity of fabrication of the supports 101, 102. Moreover, because of the comparatively narrow ultrasonic beam 107, alignment tolerances are relatively tight, and add a labor-intensive step to the manufacturing process. Ultimately, the cost of the final product, or the accuracy of the alignment of the transducers 104, 106, or both, can be adversely impacted. Furthermore, the angular offset of the transducers 104, 106 requires an inefficient use of space, and therefore impedes the desire to reduce the overall size of the device 100 for use in certain applications.
What is needed, therefore, is an apparatus that overcomes at least the drawbacks of known transducers discussed above.